Joel:
The lock I submitted is from a Gardner 1/2 stock I own. I'm only about 25 miles from Geneva, where Gardner's resided.
He died February 23, 1882 and according to his obituary, he was 88 years old. Apparently he went blind in his early 70's.
As you know, he was a very competent gunmaker, and most of the rifles I've seen by him are mule ears.